Apparatus for uplink multi-antenna communication based on a hybrid coupler and a tunable phase shifter

Embodiments of front-end module (FEM) circuitry and a communication device are generally described herein. In some embodiments, the FEM circuitry may be configured to provide uplink (UL) multiple-input multiple-output (MIMO) signals and/or UL carrier aggregation (CA) signals for transmission by the communication device. The FEM circuitry may comprise a hybrid coupler to generate a first antenna transmit signal and a second antenna transmit signal. The FEM circuitry may further comprise one or more tunable phase shifters. In some embodiments, the phase shifters may phase-shift a first radio frequency (RF) signal and a second RF signal according to a 90 degree phase difference to generate the hybrid coupler input signals. Accordingly, the antenna transmit signals may be transmitted according to the UL-MIMO configuration.